The invention relates to an outdoor air cooled condenser assembly for use in large commercial or industrial refrigeration installations, and to methods of controlling condensing temperatures in such condenser assemblies.
In the past, various methods have been proposed for controlling the effective condenser capacity, such as providing variable dampers, fan speed controls, fan cycling and the like. The conventional method predominantly used in commercial and industrial refrigeration is condenser flooding in which the effective area of the condenser is restricted by liquid refrigerant back flooding in the condenser coil in order to regulate or maintain compressor head pressures, particularly under cold ambient conditions. However, condenser flooding requires a large volume of refrigerant which is expensive and the volume needed may exceed the amount required for the normal refrigeration requirements of the evaporators in the refrigeration system, and the other proposed methods have not been totally satisfactory for a number of reasons since they either have used ambient air temperature as a control basis or they have used the refrigerant conditions in a single refrigeration system as a control basis for a multiple system condenser. Sensing ambient air ignores heat rejection load changes as a load factor, and sensing refrigerant conditions of a single refrigeration circuit in a multiple system condenser erroneously presumes that all system circuits have the same condensing needs and should respond to the same conditions as the single circuit being sensed. For example, if the circuit being sensed cycled off because evaporator temperatures were satisfied or the evaporators go into a defrost cycle, then all other system circuits in the multiple condenser would also lose their condensing action and be inoperative because the first system circuit detects no load.